Arrangement for axially securing rotating blades in arotor, and gas  turbine having such an arrangement

ABSTRACT

An arrangement for axial locking of rotating blades in a rotor is provided. The arrangement includes a shaft collar, a projection, plate-like sealing elements, and a blocking element. The sealing elements are provided for axially securing the rotating blades. At least one sealing element has an opening for securing the sealing elements against displacement in the circumferential direction. The blocking element is inserted in a recess from the end side of the shaft collar and blocks the displacement path of the sealing element. In order for the blocking element to be secured against unintentional releasing, the blocking element is fastened on the rotor disk using plastic deformation.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International Application No. PCT/EP2008/053271, filed Mar. 19, 2008 and claims the benefit thereof. The International Application claims the benefits of European Patent Office application No. 07007088.3 EP filed Apr. 4, 2007, both of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention refers to an arrangement for axial locking of rotor blades in a rotor, with a shaft collar, on the outer periphery of which provision is made for rotor blade retaining slots which extend in the axial direction of the rotor and in which rotor blades, with blade roots which correspond to the rotor blade retaining slot, are arranged in each case, with a projection which is arranged on an end-face side surface of the shaft collar in the region of the retaining slots, in which projection a radially outwardly open encompassing slot is provided and with radially inwardly open locking slots which are arranged in each rotor blade and which lie radially opposite the encompassing slot in each case, wherein for axial locking of the rotor blades provision is made for plate-like sealing elements which in each case engage in the encompassing slot and in the locking slot, forming an end-face sealing ring in the circumferential direction, wherein at least one of the sealing elements has a means for securing the sealing elements against displacement in the circumferential direction. In addition, the invention refers to a gas turbine with such an arrangement.

BACKGROUND OF INVENTION

Rotors of gas turbines are known in which turbine rotor blades, which are arranged on the outer periphery in rotor blade retaining slots, are secured against axial displacement by means of sealing plates. In this case, to fasten these sealing plates on the rotor by means of riveting is known for example from U.S. Pat. No. 3,957,393.

Furthermore, an arrangement according to FIG. 1 is known. It shows a generic-type arrangement in a plan view, and FIG. 2 shows an arrangement in a cross section according to the line of intersection II-II in FIG. 1. For each rotor blade 14 which is to be secured against axial displacement inside its rotor blade retaining slot 12, two slightly overlapping sealing plates 16 are provided as sealing elements which in each case cover by half the end-face opening of the rotor blade retaining slot 12. Each sealing plate 16 by its radially inner end 18 is inserted in an encompassing slot 20 which is provided on a rotor disk 19 on the end face, and by its radially outer end 22 is inserted in a locking slot 24 which is provided on the underside 26 of a platform 28 of the rotor blade 14. In order to secure each sealing plate 16 against displacement in the circumferential direction U, a rectilinear metal strip 30, which extends essentially in the radial direction of the rotor 23, is fastened on each sealing plate. Each metal strip 30 terminates at its radially outer end 32 in a uniformly converging point 34. Chamfered edges 36 are provided on the platforms 28 of the rotor blades 14, wherein two oppositely disposed edges 36 of directly adjacent turbine rotor blades 14 form in each case a recess 38 which tapers to a point and into which the point 34 of the metal strip 30 can project and abut for securing the sealing plate 16 against displacement in the circumferential direction U.

The sealing plates 16 furthermore cater for separation of two regions 37, 39 in which on the one hand cooling air can enter and on the other hand some of the hot gas can possibly enter.

For fastening the metal strip 30 on the sealing plate 16, two parallel slots 40 are provided in the last-named, through which the metal strip 30, which is already pre-bent into a U-shape, is inserted. Before installing the sealing plate 16 on the rotor disk 19, the end 41 of the metal strip 30 opposite the point 34 is already bent into the position which is shown in FIG. 2 for the fastening of the metal strip 30.

After installing the rotor blades 14 in the rotor disks 19, the sealing plates 16 with the pre-installed metal strips 30 are threaded one after the other into the endlessly encompassing slot 20 which is arranged on the rotor disk 19, and into the locking slot 24 which is arranged on the underside 26 of the platform 28. The sealing plates 16 are positioned along the circumference of the encompassing slot 20 so that each metal strip 30 lies opposite a recess 38. The points 34 of the metal strips 30 are then bent into the recesses 38 in order to exclude displacement of the sealing plates 16 in the circumferential direction U.

Since the metal strips may be bent only once on account of the enormously high mechanical requirements, when exchanging a rotor blade in the event of a service the metal strip which is then bent up is to be replaced by a new metal strip. Furthermore, the slots which are provided for accommodating the metal strips in the sealing plates weaken the said sealing plates.

SUMMARY OF INVENTION

It is the object of the present invention to disclose an alternative arrangement for securing the sealing elements against a rotating displacement in the circumferential direction, in which the installation and removal times are improved. The provision of a gas turbine with such an arrangement is a further object of the invention.

The object which is focused upon the arrangement for axial locking of rotor blades in a rotor is achieved by means of the features of the claims.

The invention provides that in the case of the generic-type arrangement the means for securing the sealing elements against displacement in the circumferential direction comprise an opening which is provided in the sealing element and also a recess which is provided in the side surface of the shaft collar and approximately aligns with the opening, and a positionally locked blocking element which is seated in the recess and in the opening. The invention avoids the previous configuration in which a metal strip which is hooked into the sealing element engages in a form-fitting manner in a recess. Instead of the metal strip, a blocking element is now provided which can be inserted into the recess which is provided on the shaft collar on the end face. The blocking element blocks displacement of the sealing element in the circumferential direction since, being arranged in the region of the sealing element, it extends transversely to the encompassing slot in which the sealing element is seated and in the process engages in the opening which is provided on the sealing element. A negligible and tolerable clearance of the sealing element along the encompassing slot is possible only insofar as the width of the opening as seen in the circumferential direction is larger than the width of the blocking element which is to be considered in the circumferential direction.

By using a blocking element which engages in the opening of the sealing element and is fastened on the end face on the shaft collar by means of caulking which plastically deforms the blocking element, a particularly reliable and simple axial securing of the sealing element against displacement in the circumferential direction can be achieved. Furthermore, installation is to be accomplished quickly and simply. For this purpose, the blocking element is to be plastically deformed on the end face with a suitable caulking tool, for example a tool in the style of a hammer and chisel, so that it abuts in the recess under tension. As a result, an exceptionally reliable frictional engagement between the wall of the recess and the blocking element is brought about, which reliably prevents the unwanted loosening of the blocking element during operation of the gas turbine. For removing the blocking element, the deformed region of the blocking element can be removed by grinding and in this way the frictional engagement is loosened for removal.

In addition, with the construction according to the invention the slots which were provided for fastening the locking plate on the sealing element and previously weakened the sealing element are dispensed with. The rigidity of the sealing element is subsequently further increased, also its sealing effect.

Advantageous developments are disclosed in the dependent claims.

In an advantageous development of the invention, the blocking element, with regard to its installed position, is formed in the shape of a wedge in cross section in the region of the recess and moreover comprises a bolt which projects on the end face and which can be inserted into the opening of the sealing element. As a result of the wedge shape of the blocking element and of the recess which corresponds to the wedge shape a defined position of the blocking element in the rotor is predetermined. Furthermore, the orientation of the wedge shape of the recess is selected so that the converging side walls point outwards, in the same way as the flanks of the blocking element which correspond to them. As a result, the wedge-shaped blocking element is braced outwards under centrifugal force action and in the process wedges or jams further in the recess which further increases the frictional engagement between the flanks and the side walls and makes an unwanted loosening of the blocking element more difficult. Consequently, a particularly reliable arrangement can be disclosed as a result of this.

According to an alternative development of the invention, the recess which accommodates the blocking element is open as seen in the radially outward direction. In this case, the blocking element which is inserted therein can be plastically deformed on the circumferential side, with regard to the rotor, instead of the end-face deformation. As long as provision is then still made for pockets which are additionally arranged in the sidewalls of the recess on the circumferential side, into which parts of the deformed material of the blocking element can deflect, a form-fit for positional locking of the blocking element can additionally also be provided in addition to the caulking of the blocking element. As a result of this, the blocking element is especially reliably safeguarded against loss.

According to a further advantageous development, the recess, extending in the axial direction of the rotor, is arranged in the side surface of the shaft ring in such a way that it extends right into the encompassing slot. Weakening of the shaft collar or of a rotor disk which preferably forms the shaft collar is avoided in this case. Therefore, the opening which is provided on the sealing element is then provided on the radial inner end of the sealing element. This region of the sealing element heats up the least during operation so that the rigidity and the temperature resistance of the sealing element are not impaired as a result of the opening.

It has been proved to be especially advantageous if every other sealing element, or each sealing element, has the means for securing the sealing elements against displacement. The arrangement is expediently provided on a rotor of a stationary gas turbine which is exposed to throughflow in the axial direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained based on a plurality of exemplary embodiments which are shown in a drawing. Further advantages and features result from the explanation. In the drawing:

FIG. 1 shows the arrangement for axial locking of rotor blades in a rotor according to the prior art,

FIG. 2 shows the cross-sectional view according to FIG. 1 along the line of intersection II-II,

FIG. 3 shows the detail of a plan view of a rotor disk with a rotor blade arranged thereupon as an arrangement for axial locking of the rotor blade by means of a sealing element,

FIG. 4 shows a perspective view of a blocking element according to the invention, and

FIG. 5 shows a perspective view of a blocking element which is inserted into the recess of the rotor according to a second development.

DETAILED DESCRIPTION OF INVENTION

FIG. 3 shows a detail of the end-face plan view of the shaft collar 21, which is formed by a rotor disk 19, of a rotor 23 of a gas turbine. The rotor 23, which is rotatable around the rotational axis 50, has rotor blade retaining slots 12 which are distributed on its outer periphery 52 along the circumference U and extend in the axial direction, into which slots a rotor blade 14, with a blade root 54 which is constructed corresponding to the rotor blade retaining slot 12, in each case can be inserted. A rotor blade 14 is already inserted in the rotor blade retaining slot 12 which is shown in the middle in FIG. 3. As in the case of the prior art which is shown in FIG. 1 and FIG. 2, a projection 58 or widening, with a radially outwardly open encompassing slot 20 therein, which extends in the axial direction, is arranged on an end face of the rotor disk 19 or on an end-face side surface 56 of the shaft collar 21. The encompassing slot 20 for example is arranged radially further inwards than the rotor blade retaining slots 12. The rotor blade 14 has a platform 28 which is arranged between blade root 54 and the profiled blade airfoil and on the underside of which provision is made for a locking slot 24 which is open towards the encompassing slot 20 and in this case lies opposite this. In a similar manner to the prior art, a sealing element 42 is inserted into the endlessly encompassing slot 20 and in the locking slot 24 and secures the rotor blade 14 against displacement along the rotor blade retaining slot.

In contrast to the nearest prior art, the sealing element 42 completely covers the end-face opening of one of the rotor blade slots 12. In this way, only one of the rotor blades 14 is secured in each case by one of the sealing elements 42 against displacement along the rotor blade retaining slot 12.

The sealing elements 42, however, as in the case of the prior art, can be distributed over the circumference so that two directly adjacent sealing elements engage by half in the locking slot 24 of the rotor blade 14 in each case. Then two adjacent sealing elements secure one of the rotor blades 14 against axial displacement.

Similar to the prior art, a completely installed ring of sealing elements 42, which slightly overlap in each case, forms a sealing ring which separates a region 37 which is exposed to throughflow by a cooling medium from a further region 39 in which a hot gas can possibly be encountered (FIG. 2).

In order to secure the sealing element 42 itself against displacement in the circumferential direction, an opening 63, which can be a cutout but also a hole, is provided on the radially inner end 61 of the sealing element 42.

Furthermore, a recess 65, which extends essentially in the axial direction of the rotor 23, i.e. parallel to its rotational axis 50, is provided on the side surface 56 of the shaft collar 21 in the region of the projection 58 in each case. Each recess 65 has two oppositely disposed side surfaces 66 which, as seen in the outward direction, extend towards each other in a wedge-like manner, but do not touch, forming a gap.

Instead of an outwardly open recess 65, an outwardly closed recess can also be provided. In this case, the two side walls 66 which extend towards each other meet in a rounded point.

The blocking element 67 which is perspectively shown in FIG. 4 can be inserted into the recess 65. The blocking element 67 comprises a section with a wedge shape which corresponds to the recess 65, with flanks 70 which extend towards each other, and a bolt 69 which is arranged on the wedge-shaped section on the end face. With the blocking element 67 inserted in the recess 65, its bolt 69 engages in the opening 63 of the sealing element 42.

In total, therefore, the means for securing the sealing element 42 against displacement in the circumferential direction U comprises the opening 63 in the sealing element 42, the recess 65 which is arranged in the end face of the rotor disk 19, and also the blocking element 67 which can be inserted into the recess.

A negligible and tolerable clearance of the sealing element 42 along the encompassing slot 20 is possible only insofar as the width of the opening 63 as seen in the circumferential direction is larger than the width or the diameter of the bolt which is to be considered in the circumferential direction. In order to achieve an especially impermeable separation of the region 37 from the region 39, the width of the opening 63 preferably corresponds essentially to the diameter of the bolt 69.

After inserting the blocking element 67 in the recess 65, the blocking element is slightly plastically deformed by means of a caulking process. The blocking element 67 in this case is plastically deformed in the region 71. As a result of this, the still existing, but negligible, clearance for inserting the blocking element 67 is removed so that a secure seating of the blocking element 67 results. As a result of removing the clearance, the flanks 70 are pressed onto the sidewalls 66. As a result of this, a reliable frictional engagement is created between the walls 66 of the recess 65 and the flanks 70 of the blocking element 67 which reliably prevents the unwanted loosening of the blocking element.

The caulking process can be carried out by means of a suitable chisel which is slightly rounded at the point, which when placed on the blocking element in the region 71 is provided with a hammer blow. For controlled positioning of the chisel the blocking element has an end-face premachined depression 71 in which the chisel is to be placed.

An alternative development of the invention is shown perspectively in FIG. 5. In this case, the blocking element 67 which is shown from FIG. 4 is inserted in the recess 65 with only a slight alteration. Instead of the end-face depression 71 the blocking element 67 which is to be used for FIG. 5 has two depressions 71 on the generated surface side (circumferential side), with regard to the rotor, as an aid for the caulking process and which, providing the blocking element 67 is inserted in the recess 65 according to FIG. 5, in each case lie opposite a pocket 72 which is provided in the sidewalls 66 on the circumferential side. By means of a caulking process according to the aforesaid manner the material of the blocking element which is adjacent to the depressions 71 can be introduced into the pockets 72 so that a form-fit results for secure positioning of the blocking element 67 in the recess 65.

In all, an arrangement is disclosed by the invention in which the disadvantages which are known from the prior art are eliminated by a blocking element, which is inserted from the end face of the shaft collar into a recess, blocking the displacement path of the sealing element. So that the blocking element itself is secured against unwanted loosening this is fastened on the rotor disk by means of plastic deformation. 

1.-8. (canceled)
 9. An arrangement for axial locking of rotor blades in a rotor, comprising: a shaft collar; a projection, arranged on an end-face side surface of the shaft collar in a region of a plurality of rotor blade retaining slots; a plurality of plate-like sealing elements; and a blocking element, wherein on an outer periphery of the shaft collar the plurality of rotor blade retaining slots are provided, each rotor blade retaining slot extends in an axial direction of the rotor, wherein the plurality of rotor blades are arranged in the shaft collar, each blade root corresponding to a rotor blade retaining slot, wherein a radially outwardly open encompassing slot is provided in the projection, wherein a radially inwardly open locking slot is arranged in each rotor blade and lies radially opposite the encompassing slot, wherein the plurality of plate-like sealing elements are provided for axial locking of the plurality of rotor blades, each rotor blade engages in the encompassing slot and in the locking slot, forming an end-face sealing ring in a circumferential direction, wherein at least one of the plurality of sealing elements includes an opening for securing the plurality of sealing elements against a displacement in a circumferential direction, wherein a recess is disposed in a side surface of the shaft collar, the recess approximately aligns with the opening, wherein the blocking element is seated in the recess and includes a bolt which projects on a first end face of the blocking element and engages in the opening, and wherein the blocking element is safeguarded against loss using caulking which plastically deforms the blocking element.
 10. The arrangement as claimed in claim 9, wherein the blocking element includes a section that is formed in a shape of a wedge in cross section in a region of the recess.
 11. The arrangement as claimed in claim 10, wherein the recess is formed corresponding to the wedge shape of the blocking element, and wherein two sidewalls of the recess are inclined towards each other as seen in a radially outward direction.
 12. The arrangement as claimed in claim 9, wherein the recess is open in the radially outward direction.
 13. The arrangement as claimed in claim 12, wherein a plurality of depressions are provided in the sidewalls of the recesses on the circumferential side of the rotor, and wherein the blocking element is at least partially introduced into the plurality of depressions as a result of the plastic deformation.
 14. The arrangement as claimed in claim 9, wherein the recess is closed in the radially outward direction.
 15. The arrangement as claimed in claim 9, wherein the shaft collar is formed by a rotor disk.
 16. The arrangement as claimed in claim 9, wherein at least every other sealing element includes an opening for securing the plurality of sealing elements against displacement.
 17. The arrangement as claimed in claim 9, wherein a depression is disposed in a second end-face of the blocking element, and wherein the depression is used as a predetermined position at which a chisel may be used to strike the blocking element in order to assist in a caulking process.
 18. A gas turbine, comprising: an arrangement, comprising: a shaft collar, a projection, arranged on an end-face side surface of the shaft collar in a region of a plurality of rotor blade retaining slots, a plurality of plate-like sealing elements, and a blocking element, wherein on an outer periphery of the shaft collar the plurality of rotor blade retaining slots are provided, each rotor blade retaining slot extends in an axial direction of the rotor, wherein the plurality of rotor blades are arranged in the shaft collar, each blade root corresponding to a rotor blade retaining slot, wherein a radially outwardly open encompassing slot is provided in the projection, wherein a radially inwardly open locking slot is arranged in each rotor blade and lies radially opposite the encompassing slot, wherein the plurality of plate-like sealing elements are provided for axial locking of the plurality of rotor blades, each rotor blade engages in the encompassing slot and in the locking slot, forming an end-face sealing ring in a circumferential direction, wherein at least one of the plurality of sealing elements includes an opening for securing the plurality of sealing elements against a displacement in a circumferential direction, wherein a recess is disposed in a side surface of the shaft collar, the recess approximately aligns with the opening, wherein the blocking element is seated in the recess and includes a bolt which projects on a first end face of the blocking element and engages in the opening, and wherein the blocking element is safeguarded against loss using caulking which plastically deforms the blocking element.
 19. The gas turbine as claimed in claim 18, wherein the blocking element includes a section that is foamed in a shape of a wedge in cross section in a region of the recess.
 20. The gas turbine as claimed in claim 19, wherein the recess is fanned corresponding to the wedge shape of the blocking element, and wherein two sidewalls of the recess are inclined towards each other as seen in a radially outward direction.
 21. The gas turbine as claimed in claim 18, wherein the recess is open in the radially outward direction.
 22. The gas turbine as claimed in claim 21, wherein a plurality of depressions are provided in the sidewalls of the recesses on the circumferential side of the rotor, and wherein the blocking element is at least partially introduced into the plurality of depressions as a result of the plastic deformation.
 23. The gas turbine as claimed in claim 18, wherein the recess is closed in the radially outward direction.
 24. The gas turbine as claimed in claim 18, wherein the shaft collar is fanned by a rotor disk.
 25. The gas turbine as claimed in claim 18, wherein at least every other sealing element includes an opening for securing the plurality of sealing elements against displacement.
 26. The gas turbine as claimed in claim 18, wherein a depression is disposed in a second end-face of the blocking element, and wherein the depression is used as a predetermined position at which a chisel may be used to strike the blocking element in order to assist in a caulking process. 